1. Field of the Invention
This invention relates to a method of removing particles such as foreign matter and dust from a flexible support (hereinafter referred to merely as "a support"), and an apparatus for practicing the method (hereinafter referred to as "a dust removing apparatus").
2. Terminology
The term "support" as used ,herein is intended to mean a flexible belt-shaped article having a width of several centimeters to several meters, a length of more than several tens of meters, and a thickness of several micrometers to several hundreds of micrometers. The belt-shaped article is made of a plastic film of polyethylene terephthalate, polyethylene-2, 6-napthalate, cellulose diacetate, cellulose triacetate, cellulose acetate propionate, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyimide or polyamide. Alternatively, the belt-shaped article is paper coated or laminated with .alpha.-polyolefin such as polyethylene, polypropylene or ethylene butane copolymer or is a metal foil of aluminum, copper or tin. The flexible belt-shaped product includes one on which a preliminary manufactured layer is formed.
The support is coated with a coating solution such as a photo-sensitive coating solution, a magnetic coating solution, a surface-protecting coating solution, a charging-preventing coating solution, or a smoothing coating solution, depending on its purpose of use. After the coating solution thus applied has been dried, the support is cut into pieces having a predetermined length and width. Typical examples of the product are photographic films, photographic papers, and magnetic tapes.
However, this terminology is by way of example only and is not intended to limit the invention.
3. Background Art
In a conventional method of removing particles, such as foreign matter or dust from a support (hereinafter referred to as "a dust removing method"), a piece of unwoven cloth or blade suitably held is pushed against the support so that the particles are caught by the piece of unwoven cloth or blade. In another conventional dust removing method, a stream of clean air is applied to the support at high speed so that the particles are separated from the support and led to a suction port. These methods are of dry type. On the other hand, a wet type dust removing method has been known in the art in which the support is immersed in a washing solution tank, in which the particles are separated from the support by ultrasonic vibration. In another conventional wet type dust removing method, a washing solution is applied to the support, and an air stream is applied to the support at high speed and sucked therefrom (cf. Japanese Patent Application Publication No. 13020/1974).
The above-described conventional dust removing methods still suffer from several disadvantages.
For instance, in the method in which the particles are caught by the unwoven cloth or blade, the support may be scratched or electrostatically charged by the friction, or the fibers of the unwoven cloth may stick to the support.
The dust removing method using the high speed air stream is effective in removing relatively large particles of several tens of micrometers or more from the support. However, it is scarcely effective in catching relatively small particles or particles strongly adhering to the support.
In the wet type dust removing methods, the equipment is large in scale. Furthermore, in removing particles from the support running at high speed, a large quantity of mist is produced which sticks to the peripheral devices and to the support from which the particles have been removed.
In order to eliminate the above-described difficulties the present applicant has proposed a dust removing method (Japanese Patent Application (OPI) No. 150571/1984, the term "OPI" as used herein meaning an "unexamined published application"). In this method, as shown in FIGS. 1 and 2, a solvent is applied to the surface of a support 1. While the solvent remains on the support 1, two stationary plates are pushed against the surface of the support 1 to remove the particles 18 together with a part of the solvent from the support.
Thereafter, the inventor has conducted intensive research on a more effective dust removing method and an apparatus for practicing the method, and accomplished the present invention.